Realistically I don't think programmers type prose all that much more frequently than college students. Programming tends to involve lots of symbols, and most of the typing is in small edits rather than paragraphs. College students write long essays and term papers, whereas I rarely write anything longer than an in-depth comment on Hacker News. I agree that it makes sense that programmers type faster due to the general correlation with technology usage, but I'm still quite surprised by the magnitude of the difference.